274 COALFIELDS AND COLLIERIES OF AVSTRALIA. 



made with, those furthest in-bye. These pillars are in different 

 stages of attack at the same time from one cut-through ; that- 

 furthest in-bye being of course most advanced. 



The ventilation is carried out by means of three Schiele 

 fans, 5ft., 10ft. and 12ft. in diameter, respectively, and one 

 furnace. 



The disposal of the water in the mine is as complicated 

 as the arrangement of the ventilation. This is on account of 

 the extensive workings, and various hollows, and the necessity 

 of not drowning out any particular pump, thus putting it out 

 of commission just when it is most wanted. By means of a 

 system of dams provided with gate valves, the flow of water 

 can be directed to different places; and if too much for the 

 pumps, it is diverted for the time being to old dip workings, 



Fig. 178. Pillar Extraction with a bad roof. 



where it can do no harm. The dams are built up of brick 

 laid in cement, are 14in. to 24in. thick, and are let about 4ft. 

 into the walls. Of course a suitable locality is selected, both 

 with regard to the workings and the soundness of the rock. 

 Some dams are only about 5ft. high, and any excess of water 

 f^ys over the top. Others completely stop the heading in 

 which they are placed, being built right up to the roof. The 

 dam is given a convex curve towards the impounded water, but 

 as there is no head to speak of, there is no necessity to make 

 the dams specially strong. The gate valves in connection 

 with the dams are Gin. in diameter. 



There are several Tangye pumps. Some are driven by 

 steam, one by oil, one by rope, and one by horse-power. The 

 latter, which has three 4in. rams, pumps water for a distance 

 of fully a mile against a head of 140ft. The rope driven pump 



